Erbium_Iodine_Carbon
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(Per)chloric Acid Cell: Possible?
I read on wikipedia that perchloric acid can be synthesized through electrolysis of aqueous chlorine at a platinum electrode. Since electrolysis of
HCl gives H2 and Cl2, would it, in theory, be possible to construct an electrochemical cell that would make dilute chlorine oxy acids from HCl in a
large excess of water?
If so, does anyone have any idea what kind of voltage/amperage/temperature the cell would need to operate at?
Edit: link to wiki page: http://en.wikipedia.org/wiki/Perchloric_acid
Thanks
[Edited on 23-10-2011 by Erbium_Iodine_Carbon]
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stygian
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I think the preffered way is acidification and disproportionation of (dilute!) chlorate solutions, likely the acids are far too potent and corrosive
to be directly produced. Perchlorates have been said to detonate after decades, chlorates as well are infamous.
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hissingnoise
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The difficulty of electrolysing conc. HCl makes it academic for all but the most demanding applications.
For perchlorate salts as oxidisers, NaClO<sub>4</sub> is the preferred starting material . . .
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dann2
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http://www.archive.org/details/pwechloratesthei001740mbp
Some reading above
Perchloric acid is easy to make from Sodium Perchlorate and HCl.
Dann2
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phlogiston
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Also, the current efficiency is likely to be terrible, because the extremely low pH is rather unfavourable. Although it may not seem the way, the
route NaCl --> NaClO3 --> NaClO4 --> HClO4 suggested by the others above is easier and more efficient.
[Edited on 23-10-2011 by phlogiston]
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Erbium_Iodine_Carbon
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Alright thanks; I'll stick with the easier salt electrolysis.
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woelen
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Quote: Originally posted by stygian  | | I think the preffered way is acidification and disproportionation of (dilute!) chlorate solutions, likely the acids are far too potent and corrosive
to be directly produced. |
Chlorate solutions do not disproportionate. Chlorate can be disproportionated into
perchlorate and chloride, but only in the molten and pure (!!) state. Potassium perchlorate was made from potassium chlorate by heating the latter
just above its melting point and keeping it at that temperature for some time, assuring that it does not become hotter. This practice is abandoned
though, due to safety concerns.
This is not the case
for normal ionic perchlorates. Stuff like KClO4, NaClO4, Mg(ClO4)2 and aqueous HClO4 up to 70% are remarkably stable at room temperature and can be
kept around in well closed containers for an unlimited amount of time. Risk of explosion only exists for covalent perchlorates (e.g. esters of
perchloric acid or anhydrous perchloric acid) and at high temperatures (e.g. when there is a fire).
Ionic chlorates also are stable and can be kept around for a very long time. I have a bottle of KClO3, 30 years old, and this is like I purchased it
yesterday.
[Edited on 24-10-11 by woelen]
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